Apparatus for deflashing molded goods



April 23, 1968 w. A. M CORMICK, JR 3,378,959

APPARATUS FOR DEFLASHING MOLDED GOODS Filed July 29, 1964 2 Sheets-Sheet1 INVENTOR illlllictmAMormickflz ATTORNEYS p 23, 19.68 w. A. MCCORMICK,JR 3,378,959

APPARATUS FOR DEFLASHING MOLDED GOODS Filed July 29, 1964 2 Sheets-Sheet2 I '9, III I, 7&7 NH

1' n i 97 i 1i 100 I I ll 4 mm I] 13 2 INVENTOR United States Patent3,378,959 APPARATUS FOR DEFLASHING MOLDED GOODS William A. McCormick,Jr., Hagerstown, Md., assignor to The Paugborn Corporation, Hagerstown,Md., a corporation of Delaware Filed July 29, 1964, Ser. No. 385,884 15Claims. (Cl. 51-13) ABSTRACT OF THE DISCLOSURE Molded goods aredeflashed in a gas pressurized chamber which has an air locking chamberat its entrance and an externally disposed dust collector Communicatingwith the gas chamber. Gas return means connect with the pressurizedchamber for recirculating filtered gas back to the pressurized chamber.

The present invention relates to an apparatus for removing trimmings,flashings, fins, etc. from cooled molded resilient pieces by use ofabrasive blasting equipment, particularly those pieces molded orotherwise formed from rubber.

Molded rubber or thermoplastic goods after they have been cooled areconventionally defiashed by abrasive blasting equipment in arefrigerated room. Such rooms must include special provisions foroperating the equipment therein because of the low operating temperaturein the room. Additionally, the refrigerated rooms include bulky dustcollectors for filtering the air in the room. The dust collector in theroom necessitates using a considerably larger room which, in turn,increases the cost of refrigerating the room. Consequently, the unitcost of the equipment and the room is so great that small manufacturersof molded good can not afford the investment.

One object of the present invention is to provide a simple andeconomical apparatus for deflashing molded goods with abrasive blastingequipment particularly with respect to greatly lowering the unit cost.

Other objects and advantages of the invention will become more apparentfrom a study of the following description and drawings wherein:

FIG. 1 is a front view of one embodiment of this invention;

FIG. 2 is a top view of the embodiment shown in FIG. 1;

FIG. 3 is a perspective partly broken away of the embodiment shown inFIGS. 1-2; and

FIG. 4 is taken along line 4-4 of FIG. 2.

Referring now to FIGS. 1-4 which show the general makeup of theapparatus, an overall housing 1 is provided and serves as a pressurechamber in which the operating unit of the apparatus is housed. As shownbetter in FIGS. 3 and 4, the housing 1 has formed heavy walls. The wallpanels are preferably formed of inner and outer sheets of plywood whichform a sandwich structure with insulation such as Fiberglas between theplywood sheets. The exterior of the housing 1 is preferably clad withgalvanized steel backers or sheets.

Housing 1 is maintained under pressure by dry air or any dry gas such ascarbon dioxide or nitrogen, supplied to the housing or pressurizedchamber 1 by tank 96 and housing inlet 97 to header 47. Housing 1 isalso provided with a pressure balancing vent 98 later described in itstop wall. The pressure in housing 1 is for example approximately 4inches W.G.(water gauge).

In the front wall of the housing there is a loading and unloadingdoorway 3 for loading and removing the rubber parts from within thehousing 1. As seen better in FIGS. 3-4, the door 5 of the housing 1 israised and lowered in tracks by the hoisting mechanism generallyindicated at 9 to expose and close off doorway 3.

The lower portion or closed position portion of tracks 7 curves andextends inwardly from the upper portion or open position of the tracks7. With this arrangement, a good tight seal is provided between door 5and doorway 3 when the door is in the closed position.

Doorway 3 of pressurized housing 1 communicates with air lock chamberwhich contains the loading and unloading equipment which will be laterdescribed. When .door 5 is closed to seal housing 1 the operator entersair lock chamber 100 through door 102 and loads the molded rubber orthermoplastic goods into loading bucket 11. Optionally operator couldload and unload through door 102 without entering air lock. The operatorthen leaves chamber 100 and closes door 102 to seal air lock chamber100. Air lock would then be purged replacing the air that entered duringthe opening of door 102 by means of injecting sufiicient quantity of thesame gas being supplied to the housing or pressurized chamber by tank 96and a branch line from pipe 97. The gas could be supplied, for example,through line 200 (shown in phantom in FIG. 2). Vent damper 202 (shown inphantom in FIG. 2) on air lock 100 would release purged air toatmosphere. As a result when doorway 3 is opened the pressure in housing1 is substantially unaffected by the pressure of the much smallerchamber 100 and there is no contamination of the room atmosphere. Whenthe rubber pieces are deflashed they are automatically unloaded into airlock chamber 100 as later described and doorway 3 is closed to sealhousing 1. Air lock chamber .100 can then be re-entered to remove thedeflashed pieces and load other pieces into bucket 11. I

Loading bucket 11 is pivotally supported on arms 13 which are in turnpivotally supported on a bracket 15 mounted in fixed manner on driveshaft 17. Drive shaft control 19 rotates the shaft 17 to in turn raisethe bracket 15, the bucket supporting arms 13 and the bucket 11supported thereby to a position adjacent to the top of the open doorwayas described in US. Patent No. 3,110,983. A side guide arm 21 pivotallyconnected to the housing 1 and an arm 13 guides or pulls the bucket 11inwardly within the doorway 3. When the bucket is raised to thisuppermost position, pressure cylinder 23 connected to the bucket supportand the bottom of the bucket 11 is actuated to extend its shaft 25connected with the bottom of the bucket to tip the bucket whereby therubber pieces loaded in the bucket will be discharged into the freezingand abrasive treating area. After discharging its load, the piston 25 isthen retracted and the drive shaft 17 is rotated in the oppositedirection to in turn lower the bracket 15, the arms 13 and the bucket 11to its original station as shown in FIGS. 1 and 2. The door 5 opensautomatically during the loading operation and is closed during thetreating steps. Once the articles are defiashed and ready for unloading,the door 5 is automatically opened again.

The above operation of the bucket loader and door 5 is included as apart of a cycle which is automatically controlled through the controlpanel 27 afiixed to the front face of the housing 1.

The rubber pieces are received from loading bucket 11 by a trough shapedendless belt type conveyor 29 as shown better in FIG. 4. The conveyor 29is formed of metal bars or slats (not shown) which extend transverselyof the conveyor travel and are connected at their ends to a continuoussprocket chain 33. The conveyor rotates around a front pair of guidesprockets 35 and a pair of rear drive sprockets 38. A pair of guidedisks 39 are rotatably mounted in side walls 41 which enclose the sidesof the conveyor trough area to provide contact with the slats of theupper deck of the conveyor 29 to compel the conveyor 29 to follow aconcave path which resembles a trough laterally inclined so that itfaces the doorway 3.

The operation of the conveyor 29 is part of the cycle controlled from apanel 27. The endless conveyor may also be formed of a wire mesh beltinstead of the bars or slats described above. The conveyor area alsoincludes a door 46 which is opened automatically through control panel27 during the loading and unloading operation but which is closed duringthe freezing and abrasive treatment. Briefly, this door consists of anupper rigid portion having a lower flexible portion. The door 46 issupported by rollers in door tracks 46 which bend inwardly adjacent thebottom of the tracks. Since the lower portion of the door 46 is flexibleit follows the curved pathway defined by the lower curved portion of thetracks. The tracks 46' for the door 46 extend upwardly above the roof ofthe conveyor area to accommodate the door in its opened position. Thesestructural details of the door are better shown in Patent No. 3,048,947;however, other suitable doors can be used.

After the rubber pieces 42 (see FIG. 3) are loaded in the conveyor andbefore they are trimmed or deflashed, they are treated with a freezingmedium 43 which can be liquid carbon dioxide, pulverized Dry Ice orother suitable freezing mediums such as liquid nitrogen. In fact, acombination of liquid carbon dioxide and liquid nitrogen can also beused. The conveyor 29 is in operation during the freezing step wherebythe pieces 42 are tumbled and turned to expose all surfaces to thefreezing action.

The freezing medium used is supplied by tank 97 to the nozzles 45 by acommon header 47 extending through and supported by the side walls 41enclosing the conveyor area.

Again, the application of the freezing medium 43 to the work pieces 42occurs in a definitely timed cycle controlled by or through controlpanel 27.

In the freezing operation, the rubber pieces 42 are differentiallyfrozen. This means that the excess trimming, flashing, etc. is frozen toa brittle state while the thicker portions of the rubber pieces are notcompletely frozen and therefore still retain some of their resiliency.With this arrangement, the brittle thin flashings are easily removed bythe abrasive action whereas the thicker portions of the pieces are notdamaged or otherwise abused by the abrasive action. The duration of thefreezing step of the cycle will vary for different size of type ofrubber pieces being treated.

After the rubber pieces have been differentially frozen in the mannerexplained above, they are then exposed to the next step of the cyclewhich is the abrasive treating cycle. As shown in FIG. 4 a rotary wheel50 is supported in a housing 52 attached to the roof-top or wall 44which joins the side walls 41 of the conveyor area to cover the top ofthe conveyor area. The wheel 50 is rotated at high speed by a motor topropel abrasive media such as fine steel shot through an opening in theroof top 44 and against the frozen rubber pieces supported in the troughshaped conveyor. During the abrasive applying step, a plug isautomatically withdrawn from the opening. A baffle plate extendinghorizontally from the freezing medium supply header 47 prevents abrasivefrom striking the header 47. The abrasive media is supplied to theblasting wheel 50 through storage bin 56 connected by passageway 57 tothe wheel itself.

For further detailed description of the rotary blast wheel itself,reference is made, for instance, to Patent Nos. 2,869,289; 2,732,666 and3,197,920. Any type of wheel assembly may be used however.

It should be noted, as mentioned above, that during both the freezingstep and the abrasive action step, the sprockets 35 and 38 are driven bya suitable motor drive mounted externally of the side walls 41 whichenclose the conveyor area. This action causes the rubber pieces totumble, rotate and otherwise change position whereby all surfaces of thepieces 42 are adequately exposed or subjected to both the freezing andabrasive treatment.

After the abrasive action has ceased, both the outer door 5 and theinner door 46 are automatically raised to open position. The directionof travel of the conveyor 29 is reversed and as seen in FIG. 4 therubber drops onto a slide plate 60 and are ultimately removed.

The abrasive and trim or flash that has been removed from the rubberpieces 42 in the trough conveyor 29 drops through the slats which makeup the conveyor 29 and onto a screen slide or chute 70 (FIG. 4) whichpermits only the abrasive and finer pieces of flashing to pass. Thisabrasive drops onto a screen conveyor (not shown) or other conveyingmeans and is fed to a scalping drum 72. In the scalping drum, theabrasive is further refined from the removed trim or flash with theflash discharged through a refuse discharge and into a collection boxwhich can be removed and emptied by the user. The specific structure ofthe scalping drum is described in Patent Nos. 2,771,189 and 3,087,615.From the scalping drum 72, the abrasive from which the larger pieces oftrim or flash have been removed is passed into an elevator 75 whichraises the abrasive upwardly to a separator 77 of an air wash type.Here, the abrasive passes through a stream of air whereby the fins andother light-weight contamination are removed. The specific structure ofthe separator can be shown in Patent No. 2,771,189.

From the separator 77, the abrasive then passes down into the storagebin 56 for the abrasive from which it passes through conduit 57 to theabrasive wheel 50. As an alternate abrasive can be branched off from thestorage bin through a feed pipe 83, bypassing the blast wheel, feedingto screw conveyor 72 for recirculation through the entire abrasivecleaning system.

The air in housing 1 is filtered by dust collector 81 which is externalof housing 1 but communicates with it through pipes and 79. Dustcollector 81 is of the type shown in Patent Nos. 3,053,031; 2,667,233;and 2,876,- 862. The air from housing 1 is drawn through pipe 90 intodust collector 81 by fan 87 mounted on the top of dust collector 81. Thedust laden air is filtered through a series of dust bags (not shown) andthe air is discharged through pipe 79 back into housing 1. Dustcollector 81 thereby completely recirculates the air in housing 1 and,although it is mounted external of housing 1, the pressure withinhousing 1 is substantially unaffected by dust collector 81. Becausehousing 1 is appreciably reduced in size, due to the external mountingof dust collector 81, the cost of maintaining the proper pressure andtemperature conditions in it is also greatly reduced.

Advantageously the same refrigerant 43 in liquid form for freezing thework load is also used to gaseous form for pressurizing housing 1. Thusthe atmosphere of housing 1 is essentially pure refrigerant. The addedgaseous refrigerant resulting from the vaporization or sublimation ofthe liquid refrigerant used for freezing the work load, is dischargedfrom vent 98 into line 103 to recondenser 105. Recondenser 105 isgenerally of the closed cycle gas refrigerator type wherein asufliciently low temperature is generated to recondense the vented gasback to liquid form where it is returned to supply tank 96 through line107 for subsequent reuse. This utilization of what would otherwise havebeen waste gas, considerably reduces operating costs.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. Apparatus for deflashing molded goods comprising a gas pressurizedchamber, pressure means connected to said chamber, deflashing means insaid chamber, air locking means connected to said chamber, dustcollecting means positioned externally of and communicating with saidchamber for removing dust-contaminated gas from said chamber, and gasreturn means connecting said dust collecting means to said pressurizedchamber for recir culating filtered gas back to said chamber.

2. The apparatus of claim 1 wherein loading means are in said airlocking means for loading and unloading said molded goods into and fromsaid deflashing means in said chamber, said air locking means includingmeans for opening and closing communication of said air locking meanswith said pressurized chamber.

3. The apparatus of claim 2 wherein automatic control means areconnected to said loading means for operating said loading meansexternally of said air locking means.

4. The apparatus of claim 2 wherein said clefiashing means includesliquid refrigerant applying means for differentially freezing saidmolded goods, and the gas for maintaining said chamber pressurized beingthe gaseous form of said refrigerant.

5. The apparatus of claim 4 wherein said pressure means includes asupply of said liquid refrigerant, and said pressure means communicatingwith said deflashing means for feeding liquid refrigerant to saiddeflashing means.

6. The apparatus of claim 5 wherein vent means are on said chamber fordischarging excess gaseous refrigerant, recondenser means beingconnected to said vent means for liquifying said excess gaseousrefrigerant, and said recondenser means being connected to said pressuremeans for recirculating said excess refrigerant back to said chamber.

7. Apparatus for deflashing molded goods comprising a gas pressurizedchamber, pressure means connected to said chamber, defiashing means insaid chamber, an air locking chamber, means for opening and closingcommunication of said air locking chamber with said pressurized chamber,and loading means in said air locking chamber for loading and unloadingmolded goods into and from said defiashing means.

8. The apparatus of claim 7 wherein said deflashing means includesliquid refrigerant applying means for differentially freezing saidmolded goods, and the gas for maintaining said chamber pressurized beingthe gaseous form of said refrigerant.

9. The apparatus of claim 8 wherein said pressure means includes asupply of said liquid refrigerant, and said pressure means communicatingwith said deflashing means for feeding liquid refrigerant to saiddefiashing means.

10. The apparatus of claim 9 wherein vent means are on said chamber fordischarging excess gaseous refrigerant, recondenser means beingconnected to said vent means for liquifying said excess gaseousrefrigerant, and said recondenser means being connected to said pressuremeans for recirculating said excess refrigerant back to said chamber.

11. Apparatus for defiashing molded goods comprising a gas pressurizedchamber, pressure means connected to said chamber, deflashing means insaid chamber, dust collecting means positioned externally of and incommunication with said chamber for removing dust-contaminated gas fromsaid chamber, and gas return means connecting said dust collecting meansto said chamber for recirculating filtered gas back to said chamber.

12. The apparatus of claim 11 wherein said deflashing means includesliquid refrigerant applying means for differentially freezing saidmolded goods, and the gas for maintaining said chamber pressurized beingthe gaseous form of said refrigerant.

13. The apparatus of claim 12 wherein said pressure means includes asupply of said liquid refrigerant, and said pressure means communicatingwith said defiashing means for feeding liquid refrigerant to saiddeflashing means.

14. The apparatus of claim 13 wherein vent means are on said chamber fordischarging excess gaseous refrigerant, recondenser means beingconnected to said vent means for liquifying said excess gaseousrefrigerant, and said recondenser means being connected to said pressuremeans for recirculating said excess refrigerant back to said chamber.

15. Apparatus for deflashing molded goods comprising a gas pressurizedchamber, air locking means connected to said chamber, pressure meansconnected to said chamber, said pressure means including a supply ofliquid refrigerant, deflashing means in said chamber, said deflashingmeans including abrasive blasting means and means for applying liquidrefrigerant from said pressure means against said molded goods todifferentially freeze said molded goods, the gas for maintaining saidchamber pressurized being the gaseous form of said refrigerant, ventmeans being on said chamber for discharging excess gaseous refrigerant,recondenser means being connected to said vent means for liquifying saidexcess gaseous refrigerant, and said recondenser means being connectedto said vent means for liquifying said excess gaseous refrigerant, andsaid recondenser means being connected to said pressure means forrecirculating said excess refrigerant back to said chamber.

References Cited UNITED STATES PATENTS 2,330,949 10/1943 Braun 51132,533,653 12/1950 Winkeljohn 51314 2,881,571 4/1959 Granata 51-314 X3,137,101 6/1964 Leliaert 513 14 X 3,110,983 11/1963 Moore 51-13 X3,137,101 6/1964 Leliaert 51-314 X 3,160,993 12/1964 McCormick 51-13 X3,279,125 10/1966 Leliaert 5113 3,284,958 11/1966 McCormick 513 19 X3,298,138 1/1967 McCormick 51-13 LESTER M. SWINGLE, Primary Examiner.

